金属键

The formation situation of the band for transition metallic carbonyl cluster compounds is analysed with the bond valence formula for atomic cluster compounds.

本文运用原子簇化合物键价计算公式，对过渡金属羰基簇合物成键情况进行了分析，利用金属键轨道数，价非键轨道数和金属配体成键轨道数计算簇合物价轨道总数。

It will be very useful to further the study of the metal-metal bond in such bimetallic phosphido-bridged complexes.

针对此类磷桥联的双金属配合物中金属-金属键的深入研究有着重大的意义。

It is illustrated that the state of density in the Earth's interior layers and the result of their distinctness.As the depth increases,temperature and pressure will increase,the composition of metallic bond and covalent bond will increase.

探讨了地球内部各圈层物质的密度状态及其差异的原因，指出了随着深度的增加，即温度和压力的增加，共价键及金属键的键性有增加的趋势。

May be an electrovalent bond , covalent bond and metallic bond mark like chemistry key.

化学键一般可分为离子键、共价键和金属键。

Usually, they are suitable to mixed crystals with metallic bond but not to those with covalent bond or ionic bond.

上述近似方法通常适用于金属键混晶系统，但对于共价键或离子键混晶系统计算结果则不理想。

The metallic material builtup by the metallic bond, its interior has massive free electron, therefore the electrical conductivity is good;When distortion the bond is not destroyed, therefore the plasticity is good

金属材料以金属键结合，，内部有大量能自由运动的电子，所以导电性好；在形变时键不被破坏，所以塑性好

The metallic bond has made develop the energy band theory arriving at a metallic bond , concrete annotation of model angry from classical free electron the nature that the metallic bond forms and metal crystal physical property.

金属键由经典的自由电子气模型发展到金属键的能带理论，具体地诠释了金属键形成的本质与金属晶体的物理性质。

Crystal lattice constants are close to other experiment results. Three kinds of chemical bonds exist among Mg and B atoms, between magnesium and boride is ionic bond and metallic bond is the predominant interaction in the layer formed by magnesium atoms. A strong covalent bond in the form of sp2 hybrid between boride atoms is the most important factors which can affect the transition temperature of MgB2. Population analysis clearly shows that electrons are transferred from Mg to B, as a result, the electron-phonon coupling in the layer of B is very strong.

规范保守赝势的计算结果表明，晶格常数与实验值误差在很小的范围内，分析了引起MgB2(001)面结构超导转变时电子浓度和偏态密度的变化情况，发现构成该超导体结构的成键有3种，着重从结构的电子浓度变化分析了其超导特性，六角蜂窝状结构中硼原子间相互作用为sp2杂化的共价键，镁原子和硼原子之间是离子键结合，镁原子层是金属键结合，镁原子的价电子部分转移到硼原子的pz轨道，部分电子为镁原子层共用。

The results show that the major contribution to DOS of Mg and Pb are the 2p orbit of Mg and the 5d orbit of Pb, followed by the 3s orbit of Mg and the 6p orbit of Pb, the 6s orbit of Pb is the smallest one. There are a large number of charges around Mg, it has the characteristics of typical metal bond. Mg and Pb share some charges to form covalent bond, but the distortion of the charge at the junction is little; the proportion of covalent bond is less than the metal bond, Mg2Pb is semimetal. The elastic modulus and shear modulus of Mg2Pb are 68.6 and 27.9 GPa, respectively. Based on Pugh empirical criterions and Poisson's ratio, Mg2Pb is brittle in nature.

结果表明：Mg和Pb对态密度的贡献主要是Mg的2p轨道和Pb的5d轨道，其次为Mg的3s轨道和Pb的6p轨道，Pb的6s轨道贡献最小；在Mg原子周围有大量的电荷存在，呈典型的金属键特征，Mg、Pb之间存在共用的电荷，有较强的离域性，以共价键形式存在，但交界电荷的畸变不大，故共价键所占比例较少，金属键所占比例较大，Mg2Pb化合物呈半金属性；Mg2Pb的弹性模量和切变模量分别为68.6和27.9 GPa，Pugh经验判据和泊松比均表明Mg2Pb具有脆性。

For the calculations of Mon (n= 2-55) clusters, the linear and planar clusters have a strong tendency to form diatomic pairs to assemble short-long bonds alternation structures which makes them like non-metallic clusters, the short bonds are characterized as covalent non-metallic bonds and the long ones are much like weak metal bonds.

本文首先计算了各种不同结构的Mon（n=2-55）原子簇，发现一维和二维Mo原子簇表现出了一定的非金属原子簇的性质，簇中原子有明显的成双原子对趋势，致使原子簇具有短-长键交替的几何结构，短键和长键分别呈现强共价键和弱金属键的特性。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。